Which of the Following Is True for ELISA

Multiple Choice

Which of the following is true for ELISA?
I An antibody,antibody 1,specific to the analyte of interest is dissolved in aqueous solution.
II Analyte is incubated with antibody 1,binding to form a complex.The fraction of antibody 1 sites bound to analyte is proportional to the concentration.
III Unbound substances are flushed from the ELISA surface and a second antibody,antibody 2,which binds to a different region of the analyte,is applied to the antibody 1-analyte complexes.
IV Antibody 2 is chemically modified to include an enzyme that converts a colorless reagent to a colored reagent.The more bound analyte,the more intense the color generated.

A) I,II,III,and IV
B) II and IV
C) I,III,and IV
D) II,III,and IV
E) I,II,and IV